1. Field of Invention
This patent application is copending with U.S. patent application Ser. No. 09/731,223. This invention relates to optical semiconductor device package, particularly to packages with focusing cups. The semiconductor device may be a light emitting device such as diode, a laser diode, . . . etc. The semiconductor diode may also be a light absorbing device such an image sensor, photo diode . . . etc.
2. Brief Description of Related Art
FIGS. 1-5 show a prior art technique of fabricating a diode package with a focusing cup. A metal plate is punched with holes 15 to yield a matrix of frames 13. Each frame has two metal plates 11, 12. The first metal plate 11 has two horizontal ends, the inner end 111 and outer end 112. The second metal plate 12 has horizontal ends, the inner end 121 and outer end 122.
In the next step, the metal plates 11, 12 are partially covered with an insulating material such as glue to form a cup 10 and bottom support 14 as shown in the top view FIG. 2. The cup is lined with reflecting coating to focus the light emitted from the diode.
Each semi-finished unit has the outer ends of the metal plates 112 and 122 extending outside the cup 10 as tabs. The section view along the section line A-Axe2x80x2 is shown in FIG. 4. The inner end 121 is mounted with the optical diode, which is wire bonded to the inner end 111.
The outer end 112 of metal plate 11 and the outer end 122 of metal plate 12 are then folded as shown in FIG. 5 to form the bottom contacts of the surface mount package.
Such a structure requires a thick support 14 to withstand the bending moment of the outer end 112 of metal plate 11 and outer end 122 of metal plate 12 as described in a copending U.S. patent application Ser. No. 09/731,223, which disclosed a method of using a pre-formed folded frame to reduce the thickness of the package.
An object of this invention is to provide a method of mass production of the folded frame structure disclosed in copending U.S. patent application Ser. No. 09/731,223. Another object of this invention is to reduce the cost of fabricating an optical diode package with a focusing cup.
These objects are obtained by preforming the folded bottom contacts of surface mount optical diodes on a metallic substrate before the substrate is diced into individual packages. The metallic substrate is cut with vertical parallel slits inside the horizontal edges of the substrate. Lines parallel to the slits are cut between the slits to form two wings for each slit. The two wings are folded to form the bottom contacts for the surface-mount package. Glues are poured into a mold over and under the metal substrate to form focusing cups and bottom support 14. The metal substrate and the glue are then diced to form individual packages. The diodes are mounted inside the cups and connected to the divided metal leads at the bottoms of the cups.